The central theme of this program project is a multidisciplinary quantitative approach to function, structure and expression in developing and adult nervous systems. There are 7 research Projects. Project 1, investigates the hypothesis that different functional classes of 8th nerve afferents project to and regenerate back to distinctive brainstem nuclei. Project 2, tests the hypothesis that pattern formation in the rodent trigeminal system depends on selective expression of growth factors and their receptors. Project 3, explores the hypothesis that different functional classes or dorsal root ganglion cells express markers for and respond to different growth factors. Project 4, poses the hypothesis that extracellular matrix molecules effect the migration of young neurons to and within the fetal cerebral cortex. Project 5, examines the hypothesis that intra-cortical connections in the mouse whisker barrels follow a specific sequence of development that depends on experience. Project 6, tests the hypothesis that behavioral performance on binocular tasks known to rely on the motion processing pathways in development is tied to development of connections into, in and from V1. Project 7, explores the hypothesis that the different patterns of activity of two classes of inhibitory neurons in the hamster barrel cortex correlate directly with connectivity in a network. These projects are supported by 6 COREs. CORE B - Scanning Stage Image Processing Computer Microscope, supports unique capabilities for quantitation, in anatomical context, of objects (cells, silver grains, stain intensities) from microscope slides. CORE C - Confocal Microscope with Volume Rendering and Object Segmentation, permits visualization of large areas of tissue in exquisite detail and extraction of relevant features from the masses of neural processes. CORE D - Eutectics Microscope - 3D Reconstruction System, continues to provide accurate, reliable means to collect three dimensional information from single and serial sections for measurement and visualization. CORE E - Laboratory of NeuroImaging (LONI), supports communications between the cores and provides expertise and hardware for reconstruction from serial sections and other tasks. CORE F - Growth Factor Support, provides growth factors, and antibodies, and performs in situ hybridization.